Portable electric tool



J. M. ROHLFING PORTABLE ELECT-'RIC Tool.

Filed March 9. 1931 Jan. 17, 1933.

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2 Sheets-Sheet 2 J M. ROHLFING PORTABLE ELECTRIC TOOL Filed March 9.1931 Jan. 17, 1933.

Patented Jan. 17, 1933 UNITED STATES Partnr certes JOHNYM. ROHLFIKNG,O'F' PLAINFIELD, NEW JERSEY, ASSGNOE, T0 AMERICAN CAR .AND

FOUNDRY COMPANY, OF NEW' YORK, N. Y., A CORPOEZATEGEI OF NE'W JERSEY YPORTABLE Ensor-nro 'root Application filed March 9, 1931. Serial No.521,286.

This invention relates to portable tools such as drills, rea-mers lorthe like in which the motive power is electricity, and one ob` ject ofthe present invention is the provision of a reliable and eflicient toolof this character, among the advantages of which is a provision forpreventing overloading, this result being accomplished in the present instance by so constructing and arranging the driving connection betweenthe motor and the tool spindle that it may easily, quickly andautomatically be rendered inoperative when the bit encounters abnormalresistance with the result that the operation ofthe tool is stopped. Y

In portable electric tools of the 'character described, Vit frequentlyhappens that the drill or other tool, such as a reamer bit, stalls dueto encountering abnormal resistance, thus overloading the motor andsometimes burning out the armature. Tools have been constructed whichare adapted to use fuses which blow upon such overloading, but continualreplacement of fuses is an annoyance and operators frequently resort tofuses which will not blow except under very eX- treme conditions, andthe use of this type of fuse does not eifectually prevent burning out ofthe armature.

' There is a further disadvantage usually present in tools of thecharacter described in that when the bit encounters abnormal resist-ancethere is a tendency for the fields, tool housing and handles to rotatearound the armature, and if such tendency is resisted by vtl e operatorsof the tool the armature may be burned out while if the operators cannotresist this tendency the entire tool will rotate and this constitutes asource of danger to the operators. Two men are usually required to handle tools such as described here in and said tools are usuallyprovided with oppositely extending handles, one for each I man. Thesetools are usually provided with a single electric switch under thecontrol of one of the menV and during actual operation` of the tool theoperators insert a tool bit into the tool spindle, and then the switchis thrown and the circuit closed whereby the i tool commences tofunction. After the bit is inserted into the work, if the resistance tocutting or reaming, as the case may be, is not excessive, rotation ofthe bit will continue, but if the resistance is excessive there is atendency, as before mentioned, for the fields, tool housing and handlesto rotate relative to the bit around the armature of the motor, andfrequently, the operators cannot restrain this rotation and cannot throwoff the switch quickly enough to prevent rotation of the entire tool andits yhandles with the result that frequently the operators are injured.

In view of the potential danger present in tools of this character, thepresent invention contemplates the provision of what may be termed asafe reaming or drilling tool and provides a construction whicheliminates the aforesaid danger so that should either oper' ator releasethe handle either voluntarily or involuntarily due to excessiveresistance en countered by the bit, drilling or roaming operation of thetool ceases immediately.

The present invention further provides a new and improved arrangement ofgear mechanism for operating the tool spindle.

Another object of this invention is `the provision of means interposedbetween the driving motor and the tool spindle which, during operationof the tool bit, is normally retained in operative driving connectionwith the tool spindle or the driving medium therefor, but which isautomatically shifteble to be disconnected therefrom when occasiondemands.

Still another object of this invention is the provision of anautomatically operable driving gear for directly drivingl the toolspindle, which driving gear is shiftable to be freed from its drivingconnection with the spindle when the tool being driven encounters aresistance such that an operatorinvoluntarily releases the holdinghandle for the tool.

A further object of the present invention is the provision of a new andimproved gearing arrangement interposed between the driving motor of aportable tool of the character described and the tool spindle therefor,-which arrangement includes a means operable automatically uponapplication of excessive load to the tool spindle for disconnecting thedriving connection for said spindle.

This invention further contemplates the.

provision of means for breaking the electric circuit through the motor,which means is associated with and operable upon automatic disconnectionof driving means for the tool spindle; the disconnection occurring whenand if an operator releases his grasp upon the tool.

Other objects and advantages of this invention will be apparent from thefollowing description taken in conjunction with the accompanyingdrawings in which Figure 1 is a side elevation of a portable electrictool adapted for drilling or reaming, certain parts of the figure beingtaken on the line 1-1, Fig. 2, and other parts of the figure being shownin section to disclose the interior of the gear housing.

Fig. 2 is a top plan view of the tooi shown in Fig. 1. with almost allof the motor housing and motor removed to disclose the gear housing andparts therein, certain parts in the view being shown in section.

Fir. 3 is a sectional View through the gear housing taken on the line 33, Fig. 2.

Figft is a sectional view taken on the liuc 4--4 ig. 2.

Fig. 5 is a vie-w showing the interior of the gear housing, the partsbeing shown about on the line 5-5 of Fig. 1, the view also showing oneof the handles partly in section and showing also fragments of the motorlions ing, while the upper lever of the gear carrier and the upperbracket member arc omitted.

Fig. 6 is a top plan view showing the interior of the gear housing abouton the line 6--6 Fig. 1, the view also showing the handles, a' ortion ofthe motor housing, and the levers ijor operating the shift-able gearcarrier, an

ig. 7 is a fragmentary elevation oi. one of the handles, a part thereofbeing shown in section.

Referring now more particularly to the drawings, the tool is shown asone adapted for either drilling or reaming and comprises generally amotor housingr A toy which is cured a gear housing B having a neck C inwhich the upper endk of a tool spindle D is arranged, the latterprojecting from the neck and being adapted to hold a drill or reanierbit. Secured to and extending in opposiie directions from the outerhousing are handles indicated generally' at E and, more spe/citt cally7described hereinafter'.

The motor housing may be of any preferred or ldesired construct-ion andthe gear housing. is attached to its lowcr edge by means of fasteners 2which extend through meeting flanges 4. The housing carrfes a motor (notshown) having a driving shaft 8 0n the end of which the driving pinion10 is formed.

Formed in the gear housing B is a bearing support 12 receiving ballbearing assembly 14 which is alined with a bearing assembly 16 fittedagainst an annular shoulder 18 in the neck C and retained in position bya ring member 20 threadedly secured in the end of said neck. The bearingassemblies serve to journal the upper end of tool spindle D and a sleeve21 surrounds the tool spindle and is interposed between the bearingassemblies as clearly shown in Figure 1. Secured to the upper end oftool spindle D is a pinion 22 retained by a securing nut 23 on thethreaded end of said spindle. The pinion 22 is adapted to be driven bythe before mentioned motor through the gearing arrangement presently tobe described; said gearing arrangement including an intermediateshiftable gear adapted to mesh with and be freed from meshing engagementwith the pinion 22 as more clearly pointed out hereinafter.

Arranged in the gear housing B is a main driving shaft 26, to the upperend of which is secured a main driving gear 28 which is constantly inmesh with motor pinion l() to be driven thereby` As clearly shown inFig. 3, shaft 26 extends through a guide bracket indicated generally atF which rests upon the lower or bottom wall 32 of the gear housing andwhich comprises the parallel horizontally arranged arms 34 having alinedopenings in which are arranged roller bearing assemblies 36 in which theshaft 26 is journaled; the upper bearing assembly 36 resting upon ashoulder 38 extending into the aperture in the upper arm 34 while thelower bearing assembly is supported by the lower wall 32 of the gearhousing and is retained in position by a shoulder 40 formed on the lowerarm 34 at the opening therein. Intermediate its ends the shaft 26carries al pinion 42, the purpose of which will be hereinafterdescribed. In the instance shown the shaft 26 is of substantial lengthand its lower end is arranged in an opening formed in the bottom wall 32and said opening is surrounded by an internally threaded dependingflange 44 through which lubricant may be inserted into the gear housing;said flange being adapted to receive a closure (not shown). In thepresent instance the inion 42 is shown as formed integral with the shaft26, but this is merely by way of example as obviously, within thespiritof this invention, the pinion 42 may be formed independentiy ofthe shaft and be connected for rotation therewith in any suitable ordesired manner. The bracket F is formed of substantially angle-shapedparts 46 and 48, bolted together as shown at 49, the parts 46 and 48,respectively, defining the U-shaped construction illustrated thevertical portions 50 of said parts being also connected together inabutting relation by dowels 52 whereby the parts are maintained inproper position llt) to retain the shaft 26 with its associated gear 26and pinion 42 in proper relative position. As kclearly shown in F ig. 3the bracket'F is connected to the 'side wall of the gear housing B bymeans of suitable fasteners such as screws e and, if desired, to furtherretain the bracket in position, parts of the vertical portions thereofmay be slotted to receive set screws 51 which will obviously7 preventany shifting of the bracket in the gear housing.

The present invent-ion contemplates a new and improved gearingarrangement for driving the tool spindle, the arrangement including agear carrier G pivotally connected to the driving shaft 26 forhorizontal shifting movement in the gear housing, said carrier having agear which is constantly in mesh with pinion 42 and driven thereby, butwhich is normally retained out of mesh with pinion 22. The gear isadapted to mesh with pinion 22 upon shifting of carrier .Gr in onedirection, and automatically operating means are provided fordisengaging the gear from pinion 22, as hereinafter fully described.

As clearly shown in the drawings, particularly Fig. 3, the gear carrierconstitutes a gea-r housing and comprises spaced lever members `56having enlarged rear end portions 58 and parallel arms 60 between whichlatter a spindle actuating gear 62 is arranged. The arms are connectedby a shaft 6e having a bearing assembly 66 which is arranged Within thegear 62 whereby said gear is journaled for free rotation. rllhe gear 62,as clearly sh wn in the drawings is constantly in mesh with pinion a2 onshaft 26. The

levers 56 are substantially identical and are provided with theoppositeiy arranged lugs 68 through which shaft 6e extends; said lugsserving to support and position the inner race of assembly 66, while theouter race is supported by an annular member 70 secured to the gear 62.The inner race of assembly l 66 is keyed to the lower lug 68 as at 63 torei strain said race against rotation. The gear 62 is also provided withan upper shoulder 71 which overlies the. upper edge of the outer race ofassembly 66 and serves to prevent relative vertical shifting of theouterrace as will be obvious.

The rear ends 5S are the pivot ends of the levers and are provided withproj ectino` lugs 7 2 through which tie rods or connecting' bolts 74:extend. The lever members are pivoted to shaft 26 and have bearingassemblies 7 6 arranged around said shait the upper bearing assemblyresting upon the upper surface of pinion 42 and suppor ing a spacer 78upon which rests the upperassembly 36 in the bracket F. The lowerassembly 'i' 6 is supported on a spacer member S0 mounted on the lowerassembly 36'. The ends of lever arms 60 are. provided with aperturedlugs 8a receiving a pin 86 which connects the levers 56 at this end andwhich serves as a pivotal connection for a` link 88 the purpose of whichwill be hereinafter more clearly pointed out.

From the above description it is apparent that a gear carrier has beenprovided which comprises a unit consisting of afhousing for 'gear 62including spaced lever members 56 part of the actuating mechanism forshifting the gear carrier on its pivot, and now referring to Figs. 2,Ll, 5 and 6 the link 88 connected at one end to the pin 86 has its otherend pivotally connected by means of a pin 00 to one end of a pivot lever92 consistingl of spaced links 94 (see Fig. et). The level' is pivotallymounted intermediate its ends in a bracket 96 secured to the inner wallof the gear housing by fasteners 98, and has a pin 100 extending throughthe links 9e and through alined slots 102 formed in the spaced bracketarms 10a. As will be apparent the lever 92 is capable of pivotalmovement on pin 100 and also is capable of horizontal shifting in thebracket due to the slots 102. Pivotal movement of lever 92 in onedirectionY is limited by a stop pin 108 extending between the bracketarms 10a, as shown clearly in Figs. and 6. Pivotally connected to theopposite end of lever 92 is a connecting link 105, the opposite end ofwhich is secured to a crank 106 fastened to the lower end of avertically arranged rotatable shaft 108 which is arranged in a guide 110formed on the gear housing and the upper end of which projects beyondthe gear housing and carries crank 112. Connected at one end to the pin100 is a connection link 114, the other end of which is connected to acrank 116 secured to the lower end of a vertical rotatably mountedshaft- 118, the upper end of which projects beyond the gear housing andcarries a crank 120. As shown in Fig. 1, the cranks 112 and 120 arearranged adjacent the handles E andV are provided with spaced stops 122and 12d for limiting the movement of the levers 112 and 120 in bothdirections.

F or convenience the handles are designated 126 and 126, respectively;handle 126 con taining a switch mechanism which may be conventional. Theswitch mechanism is controlled by a pivoted switch lever 130 to make andbreak contact at 182 and said lever is normally retracted by a spring134.

The crank 112 has its end connected to a the disengagement occur-l pushrod 136 by means of a link 138, and said rod is shiftable in a bearing140 secured to handle 126. The free end of rod 136 er;- tends through abearing 141 forming part of a sleeve 142 which is shiftably mounted onhandle 126 and normally urged away from the motor housing A by means ofa spring 144. The forward end of the bearing 141 is adapted to engage acollar 146 on rod 136 when the sleeve 142 is shifted in one directionwhereby to shift the rod 136 and turn the link 138 and the crank 112whereby to rotate the shaft 108. Rotation of the shaft 108, due toshifting of the sleeve 142 and rod 136 will shift the link and lever 92,thereby shifting the carrier G and forcing the gear 62 in a directiontoward the pinion 22; this occurring because of the pivotal mounting ofthe lever 92, the shifting of link 105 serving to pull the linl 88. Theshifting of the carrier just described kwill not be suiicient to causethe ear 62 and pinion to mesh. Further shifting of the carrier G isrequired to cause meshing of gear 6i.' and pinion 22. This furthershifting is a desirable feature because it prevents the actuation of thetool spindle before both operators of the tool are prepared to supportthe tool in working position. The switch lever may be used to shift thesleeve 142, but ordinarily an operator will shift the sleeve 142 tocause the gear carrier G to shift as above described, prior to actuatingthe switch lever 130 to the position shown in Fig. 1, where the lever130 serves to hold the sleeve in its forwardly shifted position. Inorder to permit swinging of the lever 13() to the position shown in Fig.1, the free end of rod 136 has a lost motion arrangement in the bearingmember 141. The extent of relative movement between the sleeve 142 fromits bearing 141 and the rod 136 may be varied by means of an adjustingnut 143,

As just described, the carrier G is partially shifted by operation ofthe sleeve 142. As a matter of fact the carrier is partially shifted byeither operator, the total shifting of the carrier causing meshing ofthe gear 62 and pinion To cause further shifting of the carrier G, afterit has been partially shifted by operation of sleeve 142, the crank 120is actuated by a link 148 connected to the lower end of a pin 150 whichextends through a sleeve 152 mounted on handle 12e, and said pin extendsthrough slots 154 formed in the handle and through a spring blockarranged in the handle. lnterposed between the spring block 156 and themotor housing A is a spring 158 which normally7 urges the sleeve 152away from the motor housing whereby t0 maintain the gear 62 out ofmeshing relation with pinion 22. Then the sleeve 152 actuated againstthe compression of spring 158 it will be obvious that the link 148 willbe shifted thereby actuating crank 120 and shaft 118 tok urge link 114to force lever 92 in the slots 102, thereby pulling or shifting thecarrier G on its pivot (shaft 26) and cause meshing of gear 62 and thepinion 22. It will be apparent that sleeves 142 and 152 may be actuatedin any sequence. If sleeve 152 is actuated the carrier G will be shiftedso as to cause the to shift toward pinion but th s shifting movement isnot sufficient to cause meshing of gear 62 and pinion 22. The sleeve 142may then be actuated to cause further shifting of carrier G and meshingof gear 62 and pinion 22. The construction described prevents operationof the tool spindle D before both operators are in a position to resistthe strain iniposed upon them by operation of the tool, as, even if themotor be started, there can be no drive of the tool spindle until eachoperator shifts the sleeve underhis control a distance such that meshingof gear 62 and pinion 22 is accomplished.

During operation of this tool, should the bit encounter a tance so greatthat the operators cannot re t the tendency of the fields, housing andhandles to rotate relative to the bit, release of a handle by eitheroperator will cause an immediate retraction of the sleeve and aconsequent unmeshing of gear 62 and pinion 22. For eonveniei'ice, thesleeve 152 is provided with a latch element pivoted thereto at 17 2 andprovided with a cam surface 174 which is adapted to extend into one ofthe slots This latch permits the easy retention ofthe slee e 152 in itsadvanced position such as shown in Fig. 1, but should thc operator beforced to release handle 128, the spring 158 will. cause retraction ofsleeve 152 and the latch 1T() will be forced out of eugagen'ient withthe slot 154 because of the cam surface 174.

From the above description it will be apparent that should the bitencounter abnormal resistance to an amount such that rotl tion of thefields, housing and handles cannot be resisted by either or both of theoperators, rel-ease of either or both handles will instantly causedisengagement of the gear 62 and pinion 22, thereby eliminating dangerof injury to the operators and also pre ing burning out of the armatureof the motor.

The drawings disclose one embodiment of the invention, but they are fori strative purposes only and it is to be understood that the inventionis not limited to the speeilic details shown, as various changes in theform and proper-Vous of the construetico. may be made within the. scopeof the appended claims without departing from the yspirit of theinvention.

lVhat is claimed is 1. In an electric drill or the like, a drivingmotor, handles, a tool holding spindle, and gearing between said motorand spindle comprising a main shaft having a pinion, a gear constantlymeshing with said pinion to be driven thereby, shiftable meanssupporting said gear adapted to force the latter into driving connectionwith the spindle when shifted in one direction and to break the drivingconnection between the gear and spindle when shifted in the oppositedirection, independent lever means associated with each of the handlesand connected with the gear supporting means and adapted to be actuatedto shift the latter, said lever means being relatively so arranged as tonecessitate operation of each thereof to establish driving connectionbetween said gear and spindle.

2. ln a tool of the character described, a driving motor, a. bit holdingspindle, and gearing between the motor and spindle including a gearnormally retained out of driving` connection with the spindle butshiftable to cause driving connection with the spindle to beestablished, and a plurality of lever means for shifting the gear, eachof said means being adapted to shift the gear partially and the movementof all of said means establishing driving connection between the gearand spindle.

3. ln a tool of the character described, a driving motor, a bit holdingspindle, and gearing between the motor and spindle including a shiftablegear normally retained lout of driving relation with the spindle, andmeans for shifting the gear in bothdirections to respectively establishand break driving connection withthe spindle comprising independentlyshiftable lever means each adapted to partially shift the gear whenmoved in one direction, the combined movements of said leversestablishing driving connection of said gear and spindle and eachthereof being adapted to break the driving connection between the gearand spindle when they are shifted in the opposite direction.

4. ln a tool of the character described, a driving motor, a main shaftdriven by said motor and having a pinion, a bit holding spindle, andmeans for driving the tool spindle comprising a gear carrier shiftableabout the main shaft, a gear supported by the carrier in mesh with thepinion, handles for the tool, lever means connected to the free end ofthe carrier and operatively associated with the handles for shifting thecarrier in one direction to establish driving connection of the gear andspindle, and means operative upon release of either handle by anoperator for actuating the lever means to shift the carrier in theopposite direction to disengage the gear from the spindle.

5. In a tool of the character described, a driving motor, a main shaftdriven thereby and provided with a driving pinion, a spindle, an idlergear in constant mesh with said pinion and normally retained out ofmeshing normally retained out of driving connection with the toolspindle, lever means for shifting the idler gear into driving connectionwith the tool spindle, and means associated with the handles foractuating the lever means in one direction to connect the idler gear andspindle in driving relation, said means being so formed and arranged asto be automatically operable upon release of a handle by an operator toactuate the lever means in the opposite direction to disengage the idlergear from the spindle.

ln witness whereof I have hereunto set my hand.

JOHN M. ROHLFING.

